MiR-214-3p delays fracture healing in rats with osteoporotic fracture through inhibiting BMP/Smad signaling pathway

L.-G. Zhou, P. Shi, Y.-J. Sun, H.-Z. Liu, J.-Q. Ni, X. Wang

Department of Orthopaedics Traumatology, the Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, China. wangxin0535@outlook.com

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• Orthopedics

OBJECTIVE: The purpose of this study was to explore the mechanism of micro-ribonucleic acid (miR)-214-3p in regulating fracture healing in rats with osteoporosis.

MATERIALS AND METHODS: A total of 30 female Sprague-Dawley rats were selected and randomly divided into 3 groups, including group A [phosphate-buffered saline (PBS), n=10], group B (AntagomiR-NC, n=10), and group C (AntagomiR-214-3p, n=10). All rats underwent ovariectomy, and the osteoporosis rat model was verified by dual-energy X-ray absorptiometry 8 weeks after the operation. Then the osteoporotic fracture was established in rats via a second operation. From the successful modeling until the 6th week, 50 μL PBS (2 nmoL) was intraperitoneally injected in group A, an equal amount of AntagomiR-NC was injected in group B, and an equal amount of AntagomiR-214-3p was injected in group C once a week. At the 6th week, fracture healing of osteoporosis rats was evaluated. At the same time, the expression of miR-214-3p in the three groups was detected via reverse Transcription-Polymerase Chain Reaction (RT-PCR). Furthermore, the protein expressions of bone morphogenetic protein 2 (BMP2) and Smad4 in the three groups were detected via Western blotting (WB).

RESULTS: After ovariectomy, the bone mineral density in each group was significantly lower than that before ovariectomy, and the differences were statistically significant (p<0.05). Imaging evaluation demonstrated that compared with group A and B, there were significantly more callus tissues in group C. Meanwhile, the fracture line healing was better and blurred, and the internal fixation had no displacement and loosening. RT-PCR results indicated that the expression level of miR-214-3p in group C was significantly lower than that of the other two groups (p<0.05). WB results showed that the protein expression levels of BMP2 and Smad4 in group C were significantly higher than those of group A and group B (p<0.05).

CONCLUSIONS: MiR-214-3p delays fracture healing in rats with osteoporotic fracture by inhibiting the BMP/Smad signaling pathway.

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